Sets or writes properties for a Modbus master instance. Use this node to set the read operation timeout, write operation timeout, or both timeouts on a Modbus slave and to set the identification of a Modbus slave.


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Inputs/Outputs

  • cModbus_Masterlvclass.png reference —

    reference is the refnum associated with the object for which you want to set properties. You must wire a Modbus master instance to the reference input. Use the Create Master Instance VI to create a Modbus master instance.

  • cerrcodeclst.png error in (no error) —

    error in describes error conditions that occur before this node runs. This input provides standard error in functionality.

  • iModbus_Masterlvclass.png reference out —

    reference is the refnum associated with the object for which you want to set properties. You must wire a Modbus master instance to the reference input. Use the Create Master Instance VI to create a Modbus master instance.

  • ierrcodeclst.png error out —

    error out contains error information. This output provides standard error out functionality.

  • ipoly.png Property —

    • Property Node Details

    You can use the Property Node to simultaneously access multiple Modbus slaves with different unit IDs through a single serial Modbus master instance, as shown in the following block diagram:

    The following list describes important details about the previous diagram:

    The serial master instance 1 output can access the Modbus slave with a unit ID of 1.
    The serial master instance 2 output can access the Modbus slave with a unit ID of 2.

    You can use the Property Node to simultaneously perform read and write operations with different timeouts on different Modbus slaves through a single Modbus master instance, as shown in the following block diagram:

    The following list describes important details about the previous diagram:

    When the TCP master instance 1 output performs read and write operations on a Modbus slave, the timeouts are both 5,000 ms, which is the default value.
    When the TCP master instance 2 output performs read operations on a Modbus slave, the timeout is 4,000 ms. When the TCP master instance 2 output performs write operations on a Modbus slave, the timeout is 6,000 ms.

    Examples

    Refer to the Modbus Library.lvproj in the labview\examples\Data Communication\Modbus\ModbusLibrary directory for an example of using the Property Node function.